Grove Karl Gilbert

Grove Karl Gilbert

Gilbert, Grove Karl, 1843-1918, American geologist, b. Rochester, N.Y., grad. Univ. of Rochester, 1862. When the U.S. Geological Survey was created in the Dept. of the Interior in 1879 (to replace four surveys in the Dept. of the Interior and the Dept. of War), Gilbert was appointed senior geologist. His Report on the Geology of the Henry Mountains (U.S. Geographical and Geological Survey of the Rocky Mountain Region, 1877, 2d ed. 1880) contains the first description of a laccolithic mountain group, a form of mountain structure that he was the first to recognize and explain. The report introduced concepts of erosion, river development, and glaciation that are incorporated in modern theories of physical geology. One of the publications of the Geological Survey is Gilbert's Lake Bonneville (1890), a study of the ancient lake of which Great Salt Lake is the remnant. He mapped the ancient shores and outlets of the Great Lakes and was the first to recognize that the successive levels of the lakes were caused by the barrier of the receding glacier, which cut off the natural drainage of the region. He also published notable studies on Niagara Falls and the Niagara River, the glaciation and morphology of the Sierra Nevada, and hydraulic mining debris in the Sierra Nevada. In 1899 he accompanied the Harriman Alaskan expedition and wrote the volume Glaciers and Glaciation in its reports.

See biography by W. M. Davis in the Memoirs of the National Academy of Sciences, Vol. XXI (1926).

In 1891 in one of the most controversial moves of his career, he proclaimed that Coon Butte in Arizona was the result of a volcanic steam explosion rather than an impact of a meteorite. Gilbert had based his conclusions on a belief that if it was an impact crater then the volume of the crater including the meteorite should be more than the ejected material on the rim and also a belief that if it was a meteorite then iron should create magnetic anomalies. Gilbert's calculations showed that the volume of the crater and the debris on the rim were roughly equal. Further there were no magnetic anomalies. Gilbert argued that the meteorite fragments found on the rim were just "coincidence." Gilbert would publicize these conclusions in a series of lectures in 1895. Subsequent investigations would reveal that it was in fact a meteor crater. Ironically, Gilbert would be among the first to say that the moon's craters were caused by meteors rather than volcanos.

Gilbert is considered one of the giants of the sub-discipline of geomorphology, having contributed to the understanding of landscape evolution, erosion, river incision and sedimentation. Gilbert was a planetary science pioneer, correctly identifying lunar craters as caused by impacts, and carrying out early impact-cratering experiments. Gilbert was one of the more influential early American geologists.

He won the Wollaston Medal in 1900. Craters on the Moon and on Mars are named in his honor. Another crater on Mars was named after the ancient Lake Bonneville.